Workaround gtk postinstall failure

x11-libs/gtk+ fails to install during the world update when being
installed as a binary.  Used to work before July update.  Works when
installed from source and works installing the binary separate from
world.  There seems to be a race condition.

Containerfile

@@ -20,6 +20,7 @@ ENV LANG=en_US.UTF-8
 RUN eselect profile set "nest:${PROFILE}"
 RUN emerge --info
 RUN if [[ $PROFILE == *workstation* ]]; then USE="-harfbuzz -vaapi" emerge -v --oneshot media-libs/freetype media-libs/mesa; else true; fi
+RUN if [[ $PROFILE == *workstation* ]]; then emerge -v --oneshot x11-libs/gtk+; else true; fi
 RUN emerge -v --update --deep --newuse --with-bdeps=y @world
 RUN emerge --depclean